w900's or comparible trucks

Go to the garage section and spend some time reading about the different CAT motors. Just the basics, 6NZ was the last of the good single turbo C15's produced from 2000 to 2002, you might occasionally find one in a 2003 year model truck. Most people building glider kits with a CAT go with a 6NZ. It was as good as CAT ever got, then came MBN single turbo, the notorious "bridge" engine that bridged the gap emissions wise between 6NZ and twin turbo C15's which are in 2004 and up trucks. I have an MBN - they can be made into a good motor but it takes a little money to un-do the emissions programming that chokes them up. The twin turbo motors are great, but again, only if one is willing to spend money on aftermarket ECM programming to make them come alive.

 

I prefer CAT. I have had better service from the CAT engines than the Detroit's that I owned previously. They don't break that often, but when they do they are a bit pricey to repair. The N14 is a real workhorse. It is one of the best models Cummins has ever made. Either would be a good choice. With the radius you plan on running, you could go with most any truck and do well. If you want to find a good used truck I would see if I could find something from the mid to late 90's to the early 2000. I would definitely stay away from the new engines. I would also recommend 355 rears. Fuel mileage will be good and you still have pulling power.

I use prefer R12 in a/c but it is difficult to find and expensive. I don't like 134 and use a drop in which does a better job of cooling and for less expense.

 

CAT is a winner here, but yup. When they break down, oh do they break down. Reliable engines but when they go in the shop your wallet suddenly loses a lot of weight.
But your the driver, it's your choice.